在Swift中如何使用C中的Struct

swift 无法直接访问 c 语言的Struct。只能通过指针的方式访问。

///////－－－－－例子1开始－－－－－－－////////

The c Lib API : mycapi.h

<code style="margin: 0px; padding: 0px; border: 0px; font-family: Consolas,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",sans-serif; white-space: inherit;"><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; color: rgb(0,139);">typedef</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; color: rgb(0,139);">struct</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">{</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;">
    </span><span class="typ" style="margin: 0px; padding: 0px; border: 0px; color: rgb(43,145,175);">int</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;">  itype</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">;</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;">
    </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; color: rgb(0,139);">double</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> </span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">*</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> dx</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">;</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;">
    </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; color: rgb(0,139);">double</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> </span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">*</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> dy</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">;</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;">
</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">}</span><span class="typ" style="margin: 0px; padding: 0px; border: 0px; color: rgb(43,175);">MyObjInfo</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">;</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;">

</span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; color: rgb(0,139);">typedef</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> </span><span class="typ" style="margin: 0px; padding: 0px; border: 0px; color: rgb(43,175);">MyObjInfo</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> </span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">*</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> </span><span class="typ" style="margin: 0px; padding: 0px; border: 0px; color: rgb(43,175);">MyObjHandle</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">；</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;">

</span><span class="typ" style="margin: 0px; padding: 0px; border: 0px; color: rgb(43,175);">MyObjHandle</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> </span><span class="typ" style="margin: 0px; padding: 0px; border: 0px; color: rgb(43,175);">MyObjInit</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">(</span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; color: rgb(0,139);">const</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> </span><span class="kwd" style="margin: 0px; padding: 0px; border: 0px; color: rgb(0,139);">char</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;"> </span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">*</span><span class="pln" style="margin: 0px; padding: 0px; border: 0px; color: black;">pFile</span><span class="pun" style="margin: 0px; padding: 0px; border: 0px; color: black;">);</span></code>

add myapi.h as module

mySwiftcode :

 
///////－－－－－例子1结束－－－－－－－//////// 
 在C函数定义的需要使用的Struct 
  
typedef struct my_struct {
    unsigned char buffer[10];
} my_struct;

void my_struct_init(my_struct *my_s) {
    for (int i = 0; i < 10; i++) {
        my_s->buffer[i] = (char) i;
    }
} 

 
 
 In Swift,we have two options: 
 1. Struct on the stack 
var my_s: my_struct = ... 
 However,we have to initialize it somehow. Every struct has a default initializer 
var my_s: my_struct = my_struct(buffer: (0,0)) 
 Note that in this case thebuffer[10]has been translated to Swift as a10-tuple. 
 Now we can call: 
my_struct_init(&my_s)
println("Buffer: \(my_s.buffer)") // Buffer: (0,1,2,3,4,5,6,7,8,9) 
 2. Struct on the heap 
 This is similar to usingmallocandfreein C: 
var my_s_pointer = UnsafeMutablePointer<my_struct>.alloc(1)
println("Buffer: \(my_s.buffer)") // Buffer: (some random values)

my_struct_init(my_s_pointer)
println("Buffer: \(my_s_pointer.memory.buffer)") // Buffer: (0,9)

my_s_pointer.destroy() 
 Combine both approaches 
 The following function will initialize any struct: 
func initStruct<S>() -> S {
    let struct_pointer = UnsafeMutablePointer<S>.alloc(1)

    let struct_memory = struct_pointer.memory
    struct_pointer.destroy()

    return struct_memory
}

var my_s: my_struct = initStruct()
my_struct_init(&my_s) 

 
 C Struct 转义方法 
  
  funcblankof<T>(type:T.Type) ->T{ 
    letptr =UnsafeMutablePointer<T>.alloc(sizeof(T)) 
letval = ptr.memory 
     ptr.destroy() 
returnval 
   } 

  
    varfs =blankof(C_Struct) 
    test(&fs)) 
 
 
 
 

 在bridging-header中 需要定义 在Swift中使用的Struct 文件。 
 Bridging-Header.h 
<code style="margin: 0px; padding: 0px; border: 0px; font-family: Consolas,sans-serif; white-space: inherit;">#include "user_input.h"
</code> 
 user_input.c 
#include <stdlib.h>

struct Pointer {
    int x;
    int y;
};

Pointer *create_pointer() {
    Pointer *p = malloc(sizeof(struct Pointer));
    if (p) {
        p->x = 20;
        p->y = 20;
    }
    return p;
}

void delete_pointer(Pointer *p) {
    free(p);
}

int pointer_x(Pointer *p) {
    return p->x;
}

int pointer_y(Pointer *p) {
    return p->y;
} 
 user_input.h 
#ifndef __user_input_h__
#define __user_input_h__

typedef struct Pointer Pointer;
Pointer *create_pointer();
void delete_pointer(Pointer *p);
int pointer_x(Pointer *p);
int pointer_y(Pointer *p);

#endif 
 main.swift 
Failed on create_pointer()")
    }

    deinit {
        delete_pointer(_ptr)
    }

    var x: Int {
        get { return Int(pointer_x(_ptr)) }
    }

    var y: Int {
        get { return Int(pointer_y(_ptr)) }
    }
}

var p = CPointer()
println("\(p.x),\(p.y)")</code>

在Swift中如何使用C中的Struct

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